SwimZip Shady Days Flap Sun Hat UPF 50+ SPF 50+ Material ... Blocks 98% of UVA and UVB Rays! (Called UPF 50+ for Sun Protection Fabric). 100% Polyester Neck Flap to Help Keep the Sun Off the Neck Baseball Cap Brim to Keep Sun Off Face Adjustable Tightener on the Back of the Hat Great Accessory to Go With SwimZip's Sun Protection Rash Guard Swimsuit Sets